Mitter was born in Schönlinde (Krásná Lípa) in Czechoslovakia, but his family was expelled from there, to Leonberg near Stuttgart.

Due to the long Nürburgring track, it was possible to take part in the German Grand Prix with Formula 2 cars that were classified in their own contest.

Mitter was killed there at Schwedenkreuz while practising for the 1969 German Grand Prix with BMW's 269 F2 project.

As a suspension or steering failure was suspected, the BMW team with Hubert Hahne and Dieter Quester withdrew from the race, as did Mitter's teammate at Porsche, Hans Herrmann.

Udo Schütz, his driving partner at Porsche in the 1969 World Sportscar Championship season with whom he had won the Targa three months earlier, had survived a bad crash at the 1969 24 Hours of Le Mans, and retired.